The radio technology used in the HiPath Cordless IP solution complies with the DECT (Digital Enhanced Cordless Telecommunications) standard. The HiPath Cordless IP solution now makes the DECT standard already established for mobile voice communications also available in Voice over IP infrastructures.

The flexibility in number of users, user density, coverage, extensibility and the provision of comfort features with the up-to-date DECT Handsets characterize the system architecture of HiPath Cordless IP. The connection to the Voice over IP infrastructure of the Communication Server is made by means of the SIP protocol. This means that DECT radio cells are the perfect way to supplement SIP-capable Voice over IP systems as mobile communication solutions.

Key Features

The entire radio range managed by the system consists of DECT IP base stations that either together form a seamless network of overlapping and synchronous radio cells or individual islands of radio signals. The size of a radio cell depends on local conditions.

DECT IP base stations support the seamless handover of existing voice connections, in other words the changeover between the radio cell and a DECT handset during a call. In addition, the roaming function is made available to mobile users, i.e. the change of radio system without an existing call.

Solution Components

The HiPath Cordless IP system solution consists of the following main components:

The HiPath Cordless IP software can be activated on one of the DECT IP base stations. Nevertheless, this DECT IP base station allows making calls. The HiPath Cordless IP SW was shifted to a dedicated standard Server to realize larger configurations. This Server as well as the Server OS (openWRT) is part of the solution approach of HiPath Cordless IP.

Overview

This section gives you an overview over the most important features of HiPath Cordless IP V1.

DECT IP base station (BSIP1)

DECT IP base stations form a network of radio cells and conduct communications with the DECT handsets. Special antennae can be used for increased radio ranges. The DECT IP base stations can be fitted with an outdoor casing to protect against inclement weather.
DECT IP base stations have the complete software for DECT and IP functionality. This software does not need to be configured and administered locally on the DECT IP base stations; this can be conveniently implemented on a centralized basis by means of the HiPath Cordless IP software.

HiPath Cordless IP Server SW

The HiPath Cordless IP software has several functions, only exists once in the system and can be activated on one of the DECT IP base stations.

Function: Router and protocol converter

HiPath Cordless IP software is the interface between the IP DECT base stations on the one hand and the Communication Server on the other.
It has a router and protocol converter function whereby it controls the voice connections between the Communication Server and the relevant DECT IP base station and also converts these into a data format that can be used by the DECT base stations.
Only the HiPath Cordless IP software knows the DECT IP base stations with which the relevant handsets are associated; this is not apparent to the Communication Server. The HiPath Cordless IP software is a Gateway User agent for the Communication Server which manages the configured handsets.
The HiPath Cordless IP software is also used to register all handsets on the Communication Server; this software administers the login procedure and the active DECT handsets.

Function: Configuration and administration interface

All administration and configuration of DECT IP base stations and of the HiPath Cordless IP software itself is executed by means of the web-based management of HiPath Cordless IP software.

Function: Synchronization management

In DECT systems with a circuit-switched connection, e.g. HiPath Cordless Office systems, the synchronization information required to synchronize the base stations is derived from the UP0 connection. This is because of the IP connection of the base station not possible in the case of the HiPath Cordless IP system.
However, accurate time synchronization between the DECT IP base stations is vital for a seamless call handover.
A seamless handover cluster is formed between synchronous DECT IP base stations; calls can only be handed over seamlessly in this cluster. More clusters of this type are possible for each Communication Server, however these are not synchronized with each other. Seamless handover is not possible between different non-synchronous clusters.

Synchronization via DECT to form this seamless handover cluster (synchronization via air)
In order to synchronize with another DECT IP base station via the DECT interface, a DECT IP base station must be within the overlap area of the radio cell that forms this DECT IP base station.
In addition, the DECT IP base station can be synchronized on other DECT IP base stations, which increases the availability of synchronicity in this cluster.
In the event that synchronicity is lost, this DECT IP base station no longer accepts calls. After all ongoing calls on the asynchronous DECT IP base station have been ended, an attempt is made to resynchronize this DECT IP base station. Only then can new calls be made on this DECT IP base station.

Synchronisierung via LAN
In difference to the air based synchronization mechanisms, synchronization via Ethernet (acc. IEEE1588, PTP Precision Time Protocol) requires less configuration.
On the other hand, great demands are made on the Ethernet characteristics like symmetry, packet loss, delay, jitter (variance of delay). Therefore special requirements regarding the Ethernet components (especially the Ethernet switches) have to be considered. Exceeding of limits (especially of jitter) will lead to loss of synchronization, which will finally lead to a resynchronization process. During this process the belonging base stations are unable to establish telephone calls. The IEEE 1588 Synchronization uses a star shaped topology only. Maximally one base station works as Synchronization Master, all other base station which participates at the synchronization process works as Synchronization Slaves.

The main advantages of synchronization via LAN are:

more flexibility in the location of the DECT IP base station - no need to built synchronisation chains as with synchronisation via DECT,

less DECT IP base stations are required, because the overlapped area of DECT IP base station is less,

configuration of DECT IP systems is simplified, because all DECT IP base stations can be synchronised to only one synchronisation master

When you want to use syncronization via LAN, a project specific release is needed. Please contact product management

Communication Interfaces

The following is an overview of the communication relationships used in the solution:DECT handset - user: DECT handset, with alternative Headset oder Bluetooth headsetDECT handset – DECT IP base station (BSIP1): A call can be handed over seamlessly between the DECT IP base stations.DECT IP base station (BSIP1) – DECT IP base station (BSIP1): Accurate time synchronization between the DECT IP base stations is vital for a seamless call handover.DECT IP base station (BSIP1) – HiPath Cordless IP software: The DECT IP base stations all communicate with the HiPath Cordless IP software; the voice and signaling data is transported in this connection. The connection protocol between the DECT IP base stations and the HiPath Cordless IP software is system specific; it is IP-based and uses UDP packages in both directions.HiPath Cordless IP software – Communication Server: The SIP protocol between the HiPath Cordless IP software and the Communication Server is standards-based.HiPath Cordless IP software - time server: A time server is not absolutely necessary. The time information is used to display this when the DECT handset is idle and to file the caller list with correct data. The Communication Server can also be managed as a time server.

Features that can be made available on the Supported Devices

In addition to the local features of the handsets such as redial list or integrated phonebook, the HiPath Cordless IP solution provides the following system features on the supported DECT telephones:

group call possible between DECT handset and optiPoint / openStage (both phones ring when an incoming call is received; when the call is answered using one of the two phones, the other phone stops ringing)

Telephonebook options:

corporate directory: LDAP Access via DECT handset

group directory: Cordless internal directory (max. 400 entries)

private directory: handset internal directory

Features per supported Platform:

You can find here a detailed overview of the features with the different platforms.

Connectable Devices

Platforms
HiPath Cordless IP SW is activated on one of the base stations (small solution):

Network Requirements
If Voice over IP is to be integrated in a network environment, it is necessary to create conditions so that the voice connections can be operated smoothly by means of IP networks. The IP network must meet the general requirements for a VoIP network in relation to delays, losses and guaranteed service quality features.

In addition, the following special conditions must be met between the DECT IP base stations and the HiPath Cordless IP server software in the IP network:

these must be part of the same Ethernet segment; neither layer 3 routing via an IP router or Network Address Translation (NAT) are supported

at least 2 priority classes according to IEEE 802.1 p/q are required in the VoIP network in order to prioritize the voice data

Use of 100 Mbps full duplex for all switched LAN ports

Otherwise delays occur in the IP network, leading to synchronization and voice quality problems on the DECT handsets.

Additional requirements if using LAN synchronization:

the maximum number of three cascaded Ethernet switches are supported between the Synchronisation Master and every Synchronisation Slave

only premium class switches, which fulfill the requirements regarding Ethernet synchronization according IEEE1588, are supported.